Adjustable bed base

ABSTRACT

An adjustable bed base ( 1 ) for supporting a person ( 22 ) on a mattress ( 17 ) loosely lying on the bed base, comprising a leg part ( 2 ) and a back part ( 3 ), connected to each other by an adjusting mechanism ( 4 ) which comprises a first part ( 5 ) connected to the back part ( 3 ) and a second part ( 6 ) connected to the leg part ( 2 ), the first and second parts engaging each other and being movable with respect to each other along a predetermined curve which is determined such that the back part ( 3 ) upon movement tilts with respect to the leg part ( 2 ) and is simultaneously moved in longitudinal and height directions of the bed base ( 1 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Stage of International ApplicationNo. PCT/BE02/00016 filed Feb. 13, 2002, and claims the priority ofBelgian Application No. 2001/0102 filed Feb. 14, 2001. The entirety ofeach of those applications is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to an adjustable bed base according to thepreamble of the first claim.

With the bed base can be meant a slatted base or any other base of abed.

An adjustable bed base is for example known from U.S. Pat. No.5,537,701. The bed base described in U.S. Pat. No. 5,537,701 comprises aleg part for supporting the lower part of the body of a person lying onthe bed base and a back part for supporting the upper part of thisperson's body. By means of an adjusting mechanism, the back part isadjustable with respect to the leg part between a lying position and anupright position, in which the back part encloses an obtuse angle withthe leg part. The adjusting mechanism is constructed such that, uponmoving the back part between the lying position and the uprightposition, the back part pivots with respect to the leg part and is alsomoved in longitudinal and height directions of the bed base. As aresult, a displacement of the head end of a mattress lying on the bedbase with respect to the back part and a displacement of the foot end ofthe mattress with respect to the leg part are prevented.

The bed base described in U.S. Pat. No. 5,537,701 however has thedisadvantage that the adjusting mechanism for moving the back partbetween the lying position and the upright position comprises acomplicated construction. This complicated construction is the result ofthe fact that the adjusting mechanism comprises, on the one hand, partsfor accomplishing the pivoting movement of the back part and, on theother hand, parts for accomplishing the displacement of the back partalong the longitudinal and height directions of the bed base. This leadsto an adjusting mechanism, in which various parts move with respect toeach other during the movement of the back part.

Further, a dentist chair is known from DE-A-39 01 379 with a leg partand a back part which are movable with respect to each other. To thisend, the dentist chair comprises an adjusting mechanism which enables arotation of the back part with respect to the leg part about a virtualpivoting axis, which is located in the pelvis of the person being seatedin the chair. By this rotation about the virtual pivoting axis isachieved that a displacement of the person with respect to the chair canbe prevented.

SUMMARY OF THE INVENTION

It is an aim of the present invention to provide an adjustable bed basewith a simplified adjusting mechanism for moving the back part withrespect to the leg part between the lying position and the uprightposition, with which a displacement of the mattress with respect to thebed base is minimised.

This aim is achieved according to the invention with a bed base showingthe technical characteristics of the characterising part of the firstclaim.

In the bed base of the invention, the adjusting mechanism comprises afirst part which is fixed to the back part and: a second part which isfixed to the leg part. The first and second parts engage each other andthe first part is movable with respect to the second part along apredetermined curve. This curve is determined such, that the back partupon movement tilts with respect to the leg part and is simultaneouslymoved along the longitudinal and height directions of the bed base. Inother words, the different movements of the back part with respect tothe leg part are combined into a single movement, namely the movementalong the predetermined curve. This curve can be a segment of a circle,an ellipse, a parabola or a hyperbola, or any other curve deemedsuitable by the person skilled in the art.

Because the back part is movable with respect to the leg part along thepredetermined curve, one achieves that substantially only two parts aremovably mounted with respect to each other in the bed base of theinvention. The adjusting mechanism comprises significantly less partswhich move with respect to each other, so that its weight can bereduced. Because of this reduced weight, a motor of lower power can beused for moving the back part, which results in a lower energyconsumption.

The curve along which the first part of the adjusting mechanism is movedwith respect to the second part is preferably determined as follows. Thebending of a mattress lying on the bed base causes a lengthening of thebottom side of the mattress which contacts the bed base. If the backpart and the leg part were connected by means of a conventional hinge,the contact surface on which the mattress lies would shorten or at mostremain equal, while the bottom side of the mattress is as it werestretched. This would result in a displacement of the head end of themattress with respect to the back part and/or a displacement of the footend of the mattress with respect to the leg part of the bed base.

By the movement from the lying position to the upright position alongthe predetermined curve, it is made sure that the back part is removedfrom the leg part, so that the contact surface with the mattress islengthened. Because of this, it is possible to minimise the displacementof the mattress with respect to the leg and back parts. By applying thepredetermined curve, the movement of the back part is optimallyadjustable to the lengthening of the bottom side of the mattress. Byfurther taking into account a lengthening of the bottom of the personlying on the mattress, upon bringing him from lying to sitting position,a very comfortable movement can be achieved, in which simultaneously thedisplacement of the mattress on the bed base and the displacement of theperson on the mattress can be minimised.

In the dentist chair described in DE-A-39 01 379, the leg part and theback part are movable with respect to each other along a predeterminedcurve, namely a segment of a circle. The dentist chair is, however, notprovided for supporting a person on a mattress loosely lying on thechair. In the case of the dentist chair, the leg and back parts are eachprovided with a separate seat. So the problem of the displacement of themattress does not occur in this case. As a result, DE-A-39 01 379 doesnot teach how a displacement of a mattress with respect to the legand/or back parts can be prevented, nor how a displacement of the personon the mattress can be prevented. It is therefore not obvious that aperson skilled in the art would apply the teaching of DE-A-39 01 379 tosolve the problem of the displacement of the mattress and/or the person,especially since DE-A-39 01 379 relates to a different technical field.

Furthermore, the curve of the dentist chair described in DE-A-39 01 379is always a segment of a circle, whereas the curve in the bed base ofthe invention may, apart from a segment of a circle, also be a segmentof a parabola, an ellipse or a hyperbola, or any other curve which theperson skilled in the art deems suitable for achieving that the movementof the back part can be adjusted as good as possible to the form of thelengthening of the mattress.

In a preferred embodiment of the bed base according to the invention,the predetermined curve is a segment of a circle, the centre of which islocated on a virtual axis. This virtual axis extends substantially incross direction of the bed base and is preferably located in an areabetween, on the one hand, the separation of the top surfaces of the ofthe leg and back parts and, on the other hand, the top side of theperson's pelvis. The circular shape of the predetermined curve has theadvantage that it is easily achievable.

The movement of the back part with respect to the leg part is optimalwhen the virtual axis extends in cross direction through the pelvis ofthe person. In this way, the bed base and the person bend about the sameaxis, so that the person can be brought from lying to sitting positionor vice versa in a comfortable way. Namely, by locating the virtual axisin the person's pelvis, the displacement of the mattress with respect tothe leg and/or back parts and simultaneously the displacement of theupper and/or lower parts of the person's body with respect to themattress can be minimised. The circular shape of the curve with thevirtual axis in the person's pelvis is the simplest way of achievingthis effect according to the invention. However, it should be noted thatthis effect can also be achieved by a suitable choice of a differentshape of the curve, such as for example a suitably chosen segment of anellipse, a parabola, a hyperbola or any other curve known to the personskilled in the art.

In the case that the curve is a segment of a circle, the virtual axis islocated on a fixed location with respect to the leg part. In the othercases mentioned above, the virtual axis moves with respect to the legpart during the movement of the back part. In such case it is desirablethat the virtual axis remains within the area of the person's pelvis,for achieving the effect of optimal movement of the back part.

The adjusting mechanism of the bed base according to the invention canbe constructed in various ways. In a first preferred embodiment, thefirst and second parts of the adjusting mechanism are formed by at leastone sliding member and at least one groove for receiving the slidingmember, the at least one groove having the shape of the curve. A firstpossibility is that the sliding member is fixed to the back part andthat the groove is fixed to the leg part. For moving the back part withrespect to the leg part the sliding member is then moved in the groove.A second possibility is that the groove is fixed to the back part andthat the sliding member is fixed to the leg part. For moving the backpart with respect to the leg part, the groove is then moved over thesliding member.

The sliding member preferably engages the groove on at least two spacedapart points. In this way it can be prevented that the sliding membertilts in the groove. Since the back part is fixed to either the slidingmember, or the groove, the sliding member or the groove in itself givessufficient support for keeping the back part upright, so that nosupplemental support has to be provided below the back part for keepingthe back part upright.

In a second preferred embodiment of the bed base according to theinvention, the first and second parts of the adjusting mechanism areformed by at least one rolling member and at least one groove forreceiving the sliding member, the at least one groove having the shapeof the curve. By analogy with the first preferred embodiment, therolling member may be fixed to the back part and the groove to the legpart, or vice versa. By further analogy with the first preferredembodiment, the at least one rolling member is preferably on at leasttwo spaced apart points provided with each time a wheel, which engagesin the associated groove.

In a third preferred embodiment of the bed base according to theinvention, the first and second parts of the adjusting mechanism areformed by at least one rolling member and at least one rail over whichthe rolling member is movable, the at least one rail having the shape ofthe curve. By analogy with the first preferred embodiment, the rollingmember may be fixed to the back part and the rail to the leg part, orvice versa. By further analogy with the first preferred embodiment, theat least one rolling member is preferably on at least two spaced apartpoints provided with each time a pair of wheels which contact oppositesides of the associated rail.

The adjusting mechanism of the bed base ma further be constructed in anyother way deemed suitable by the person skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

The bed base according to the invention will be further elucidated bymeans of the following description and the appended figures.

FIGS. 1 a to 1 c show a preferred embodiment of the bed base of theinvention with the back part respectively in the lying position, anintermediate position and the upright position.

FIGS. 2 a and 2 b show how a person is brought from lying to sittingposition with the bed base of the invention.

FIGS. 3 a to 3 c show the adjusting mechanism of the bed base of FIGS. 1a to 1 c in detail.

In the figures, the invention is applied to a slatted base of a bed. Theinvention may however also be applied to any other base of a bed knownto the person skilled in the art.

DETAILED DESCRIPTION

The bed base 1 shown in the FIGS. 1 a-c is adz/provided for supporting aperson 22 on a mattress 17 loosely lying on the bed base 1. The bed base1 comprises a leg part 2 for supporting the lower part 27 of theperson's body and a back part 3 for supporting the upper part 26 of theperson's body. The leg part 2 extends from the pelvis to and beyond theperson's feet 28. The back part 3 extends from the pelvis to and beyondthe person's head. The back part 3 is adjustable with respect to the legpart 2 between a lying position (FIG. 1 a), in which the back part 3extends in line with the leg part 2, and an upright position (FIG. 1 c),in which the back part 3 encloses an obtuse angle α with the leg part 2.The successive FIGS. 1 a-c show that the back part 3 upon being movedfrom the lying position to the upright position tilts with respect tothe leg part 2 and is simultaneously removed from the leg part 2 alongthe longitudinal and height directions of the bed base 1.

The back part 3 is connected to the leg part 2 by means of an adjustingmechanism 4, which is shown in more detail in FIGS. 3 a to 3 c. Thiscomprises a first part 5 which is fixedly mounted, to the back part 3and a second part 6 which is fixedly mounted to the leg part 2. Thefirst and second parts 5, 6 engage each other and are movable withrespect to each other along a predetermined curve. This curve isdetermined such, that the back part 3 tilts with respect to the leg part2 upon movement between the lying position and the upright position, andis simultaneously moved along the longitudinal and height directions ofthe bed base 1. In this way it is achieved, that a displacement of themattress 17 with respect to the leg part 2 and the back part 3 isminimised.

In the bed base 1 shown in FIGS. 1 a-c and 3 a-c, the predeterminedcurve has the shape of a segment of a circle. The centre of this segmentis, located on a virtual axis (not shown), which extends in crossdirection of the bed base 1 and is preferably located in an areabetween, on the one hand, the separation of the top surfaces of the legpart 2 and the back part 3 and, on the other hand, the top side of thepelvis of the person 22. Within this area, the virtual axis may forexample extend through the pelvis of the person, or coincide with thebending axis about which the mattress 17 is bent as a result of themovement of the back part 3, or in any other location within the areawhich is deemed suitable by the person skilled in the art. In theembodiment shown in FIGS. 1 a-c and 3 a-c, in which the curve is asegment of a circle, the movement of the back part 3 is optimal when thevirtual axis is located in the pelvis of the person 22, sincedisplacements of the upper 26 and lower parts 27 of the person's bodywith respect to the mattress 17 can then also be prevented. However, itis also possible to choose a segment of an ellipse, a hyperbola or aparabola as shape of the curve, or any other shape known to the personskilled in the art. With such a shape, the virtual axis, about which theback part 3 is tilted, does not have a fixed position, but moves uponthe movement of the back part 3 between the lying position and theupright position. In this case the movement is optimal when the virtualaxis remains within the area specified above.

The leg part 2 of the bed base 1 of FIG. 1: is preferably fixedlymounted on the bed base 1. However, it may also be movably mounted onthe bed base 1 in longitudinal direction and/or!in height direction.

In the bed base 1 of the FIGS. 1 a-c and 3 a-c, the first part 5 of theadjusting mechanism comprises two rolling members 7 which are mountedsubstantially parallel with respect to each other in longitudinaldirection of the bed base 1. The rolling members 7 are connected to asupporting element 8 in a fixed angle β, the back part 3 being mountedon the supporting element 8. The second part 6 of the adjustingmechanism comprises two fixed elements 10 which are mountedsubstantially parallel in longitudinal direction of the bed base 1. Eachfixed element 10 is provided with a groove 11, which has the shape ofthe predetermined curve and is provided for receiving the rolling member7. The movability of the rolling member 7 in the groove 11 is ensured inthat the rolling member 7 comprises each time a wheel 9 on two spacedapart points. As these wheels 9 are spaced apart, it is furthermoreachieved that the rolling member 7 cannot tilt in the groove 11 duringstandstill, so that the rolling member 7 in itself can function assupport for keeping the back part 3 upright. This has the advantage thatproviding a support on the bottom side of the back part 3 for keeping itupright can be prevented.

In the bed base of FIGS. 1 a-c, the rolling members 7 are fixedlyconnected to the back part 3 and the fixed elements 1 p are connected tothe leg part 2; Vice versa, the rolling members 7 may also be connectedto the leg part 2 and the fixed elements 10 to the back part 3.

The adjusting mechanism 4 of the bed base of FIGS. 1 a-c comprises tworolling members 7 which engage two grooves 11. The adjusting mechanism 4may however also comprise more or less rolling members and grooves.Furthermore other embodiments are also possible for the adjustingmechanism, such as for example at least one sliding member, eachengaging at least one groove, or at least one rolling member, eachengaging around at least one rail, or other.

For moving the back part 3 between the lying position and the uprightposition, the bed base 1 of FIGS. 1 a-c is provided with a motor 12.This motor preferably comprises a piston 15 which is movably mounted ina cylinder 16. The free end of the piston 15 is rotatably mounted to across bar 13 of the first part 5 of the adjusting mechanism 4. Thecylinder is mounted to a cross bar 14 which is fixed, to the leg part.In this way, an outwards movement of the piston 15 towards the outsideof the cylinder 16 causes a movement of the back part 3 from the lyingposition towards the upright position. Vice versa, an inwards movementof the piston 15 towards the inside of the cylinder 16 causes a movementof the back part 3 from the upright position towards the lying position.The motor is preferably a linear electrical motor, but may also be anyother motor known to the person skilled in the art, such as for examplea hydraulic or pneumatic motor or other.

The different parts of the bed base 1 may be constructed in wood, metalor a plastic material, or any other material deemed suitable by theperson skilled in the art.

The operation of the bed base of FIGS. 1 a-c is as follows. For movingthe back part 3 from the lying position to the upright position, themotor 12 is operated such that the piston 15 slides out of the cylinder16. This causes the rolling members 7 to move in the grooves. Therolling members 7 follow the shape of the grooves 11 and areconsequently moved along the curve which determines the shape of thegrooves 11. As the rolling members 7 follow the shape of the grooves 11,they are simultaneously displaced and rotated. As the supporting element8, and consequently also the back part 3, are connected to the rollingmembers 7 in a fixed angle α, this is also tilted about the virtualaxis. Since the rolling members 7 engage in the grooves 11 on two spacedapart points, they are in themselves capable of sufficiently supportingthe back part 3 to keep it upright. For moving the back part 3 from theupright position to the lying position it suffices to operate the motor12 in opposite direction, so that the piston 15 slides into the cylinder16.

The tilting movement of the back part 3 with respect to the leg part 2along the predetermined curve is again clarified in FIGS. 2 a-b, inwhich the bed base 1 is shown with a mattress 17 and a person 22 on top.The mattress has a front part 18 in contact with the back part 3 and arear part 19 in contact with the leg part 2 of the bed base 1. As isusual in a bed, the mattress has a length substantially equal to thelength of the bed base 1 in the lying position, so that the: head end 20and the foot end 21 of the mattress are substantially flush with thefront and rear ends 24, 25 of the bed base 1. By the tilting movementalong the predetermined curve is achieved that the back part 3 and theleg part 2 are removed from each other upon movement from the lyingposition (FIG. 2 a) towards the upright position (FIG. 2 b), so that thetop surface of the bed base 1 is uniformly lengthened with thelengthening of the bottom surface of the mattress 17. As a result,displacements of the front 18, respectively rear part 19 of the mattress17 with respect to the back part 3, respectively the leg part 2 areminimised. In this way it can be prevented, that in the upright positionthe head end 20 of the mattress 17 protrudes with respect to the frontend 24 and that the foot end 21 of the mattress 17 protrudes withrespect to the rear end 25 of the bed base 1. Furthermore, the tiltingmovement along the predetermined curve makes it possible to prevent thatupon movement of the back part 3 the upper part 26 of the person's body22 is displaced on the front part 18 of the mattress 17, and that thelower part 27 of the person's body 22 is displaced on the rear part 19of the mattress 17. By preventing these displacements, the distance Dbetween the feet 28 of the person 22 and the foot end 21 of the mattress17 remains substantially constant upon movement from the lying positionto the upright position.

1. An adjustable bed base for supporting a person on a mattress loosely lying on the bed base, the bed base comprising a leg part for supporting the lower part of the person's body and a back part for supporting the upper part of the person's body, the back and leg parts together forming an uppermost surface of the bed base intended for loosely supporting a mattress, the back part being adjustable between a lying position in which the back part extends substantially in line with the leg part and an upright position in which the back part forms an obtuse angle (α) with the leg part, the back part being connected to the leg part by an adjusting mechanism which is provided to tilt the back part with respect to the leg part and simultaneously move the back part in the longitudinal and height directions of the bed base, the movement of the back part with respect to the leg part being defined by a predetermined curve which is determined for preventing displacement of a mattress which is loosely supported on said uppermost surface, the adjusting mechanism comprising a first part fixed on the back part and a second part fixed on the leg part, the first and second parts engaging each other and the first part being movable with respect to the second part along the predetermined curve, one of the first and second parts being shaped according to the curve.
 2. An adjustable bed base according to claim 1, characterised in that the predetermined curve is a segment of a circle with a centre located on a virtual axis, the virtual axis extending in cross direction of the bed base and being located in an area between, on the one hand, the separation of the top surfaces of the leg part and the back part and, on the other hand, the top side of the person's pelvis.
 3. An adjustable bed base according to claim 2, characterised in that the virtual axis extends in cross direction through the person's pelvis.
 4. An adjustable bed base according to claim 1, characterised in that the first and second parts of the adjusting mechanism are formed by at least one sliding member and a groove for receiving the sliding member, the at least one groove having the shape of the curve.
 5. An adjustable bed base according to claim 4, characterised in that the at least one sliding member engages in the associated groove on at least two spaced apart points.
 6. An adjustable bed base according to claim 2, characterised in that the first and second parts of the adjusting mechanism are formed by at least one rolling member and a groove for receiving the rolling member, the at least one groove having the shape of the curve.
 7. An adjustable bed base according to claim 6, characterised in that on at least two spaced apart points the at least one rolling member is provided with a wheel which engages in the associated groove.
 8. An adjustable bed base according to claim 1, characterised in that the first and second parts of the adjusting mechanism are formed by at least one rolling member and a rail over which the rolling member is movable, the at least one rail having the shape of the curve.
 9. An adjustable bed base according to claim 8, characterised in that on at least two spaced apart points the at least one rolling member is provided with each time a pair of wheels which contact opposite sides of the associated rail.
 10. An adjustable bed base according to claim 1, characterised in that the bed base is provided with a motor for moving the back part between the lying position and the upright position.
 11. An adjustable bed base according to claim 1, characterised in that the bed base is mounted in a longitudinally movable way on a supporting frame. 